NSURLConnection 发送异步请求

gistfile1.m

// 代码如下:

[NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:urlString]]
                                   queue:[[NSOperationQueue alloc] init]
                       completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
                            //异步请求完成后的操作
                       }];

// 如果要在 completionHandler 中更改界面, 需要用以下代码:

[[NSOperationQueue mainQueue] addOperationWithBlock:^ {
    //更改界面的操作
}];

// 示例如下:

[acticityIndicator startAnimating];
[NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:urlString]]
                                   queue:[[NSOperationQueue alloc] init]
                       completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
                            [[NSOperationQueue mainQueue] addOperationWithBlock:^ {
                                [acticityIndicator stopAnimating];
                            }];
                               
                            if (connectionError == nil) {
                                [data writeToFile:[NSTemporaryDirectory() stringByAppendingPathComponent:@"data.plist"]
                                       atomically:YES];
                            }
                       }];